Issu 

U.  S.  DEPARTMENT  OF  AGRICULI 


9  BUREAU  OF  ANIMAL  INDUSTRY.— BULLETIN  11 

0  I 

-)    -       m*  A.  D.  MELVIN,  CHIEF  OF  BUREAU. 


=  IE  INFLUENCE  OF  ACIDITY  OF  CREAM 
ON  THE  FLAVOR  OF  BUTTER. 


BY 
L.  A.  ROGERS, 

Bacteriologist,  Dairy  Division, 
AND 

C.  E.  GRAY, 

Formerly  Chemist,  Dairy  Division. 


WERSl'iY  OF  CAUR. 
LOS  ANGELES 

SEP  23  1952 


WASHINGTON: 
GOVERNMENT    PRINTING   OFFICE. 

1909. 


LIBRARY 

R°°M 


Issued  Junr  10,  1909. 

U.  S.  DEPARTMENT   OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— BULLHTIN  114. 

A.  D.  MELVIN,  CHIEF  OF  BUREAU. 


THE  INFLUENCE  OF  ACIDITY  OF  CREAM 
ON  THE  FLAVOR  OF  BUTTER. 


BY 

L.  A.  ROGERS, 

Bacteriologist ,  Dairy  Division, 
AND 

C.  E.  GRAY,      " 

Formerly  Chemist,  Dairy  Division . 


WASHINGTON: 

GOVERNMENT    PRINTING    OFFICE. 
1909. 


THE  BUREAU  OF  ANIMAL  INDUSTRY. 


Chief:  A.  D.  MELVIN. 

Assistant  Chief:  A.  M.  FARRINGTON. 

Chief  Cleric:  CHARLES  C.  CARROLL. 

Biochemic  Division:  M.  DORSET,  chief;  JAMES  A.  EMERY,  assistant  chief. 

Dairy  Division:  B.  H.  RAWL,  chief. 

Inspection  Division:  RICE  P.  STEDDOM,  chief;  MORRIS  WOODEN,  R.  A.  RAMSAY,  and 
ALBERT  E.  BEHNKE,  associate  chiefs. 

Pathological  Division:  JOHN  R.  MOHLER,  chief;  HENRY  J.  WASHBURN,  assistant 
chief, 

Quarantine  Division:  RICHARD  W.  HICKMAN,  chief. 

Zoological  Division:  B.  H.  RANSOM,  chief. 

Experiment  Station:  E.  C.  SCHROEDER,  superintendent;  W.  E.  COTTON,  assistant. 

Animal  Husbandman:  GEORGE  M.  ROMMEL. 

Editor:  JAMES  M.  PICKENS. 


LETTER  OF  TRANSM1TTAL. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY, 

Washington,  D.  C.,  March  29,  1909. 

SIR:  I  have  the  honor  to  transmit  herewith,  with  the  recommenda- 
tion that  it  be  published  as  a  bulletin  of  this  Bureau,  a  paper  entitled 
"The  Influence  of  Acidity  of  Cream  on  the  Flavor  of  Butter,"  by  L.  A. 
Rogers  and  C.  E.  Gray. 

The  deterioration  in  quality  and  the  development  of  objectionable 
flavors  in  butter  kept  in  cold  storage  cause  considerable  loss  to  the 
trade,  and  the  causes  and  nature  of  these  changes  have  not  been 
understood.  The  Dairy  Division  of  this  Bureau  has  been  making  a 
study  of  these  problems  during  the  past  three  years,  and  the  present 
paper  reports  investigations  in  which  quantities  of  butter  were  made 
from  cream  of  varying  degrees  of  acidity  and  stored  at  different  tem- 
peratures. It  is  believed  that  the  results  will  be  of  practical  value  to 
the  butter  manufacturers  of  the  country. 

The  authors  wish  to  express  their  appreciation  of  the  services  of  the 
various  persons  whose  cooperation  has  made  this  work  possible. 
They  are  especially  indebted  to  the  director  and  members  of  the  staff 
of  the  University  of  Wisconsin  Agricultural  Experiment  Station,  who 
kindly  allowed  the  use  of  their  creamery  and  laboratories  for  part  of 
the  work.  They  are  also  under  obligations  to  the  manager  of  the 
creamery  at  Bloomer,  Wis.,  and  to  the  several  persons  who  kindly 
scored  the  butter. 

Respectfully,  A.  D.  MELVIN, 

Chief  of  Bureau. 
Hon.  JAMES  WILSON, 

Secretary  of  Agriculture. 

3 


CONTENTS. 


Page. 

Introduction 7 

Experiments  with  butter  made  from  (.-ream  with  varying  acidity 

Discussion  of  results 11 

Determinations  of  bacteria  in  the  butter J  2 

Possible  action  of  enzymes  in  deteriorating  high-acid  butter 1~> 

Influence  of  lactic  acid  on  flavor  of  butter 17 

Result  of  producing  acidity  with  other  acids  than  lactic  arid 17 

The  manufacture  of  commercial  butter  from  sweet  cream 18 

Conclusions...  21 


THE  INFLUENCE  OF  ACIDITY  OF  CREAM  ON  THE 
FLAVOR  OF  BUTTER. 


INTRODUCTION. 

Although  much  has  been  written  about  butter,  there  is  yet  very 
little  known  about  the  changes  taking  place  in  its  chemical  composi- 
tion, the  relation  of  these  changes  to  the  changes  in  flavor,  the  causes 
which  produce  them,  or  the  factors  which  control  their  progress.  It 
becomes  necessary,  therefore,  to  work  out  one  by  one  the  various 
conditions  which  cause  or  control  the  changes  in  the  composition  and 
flavor  of  butter.  The  difficulty  of  controlling  conditions  exactly  and 
at  the  same  time  making  normal  butter  renders  it  hard  to  determine 
the  part  played  by  any  one  factor.  However,  it  is  only  by  limiting 
the  variations  so  far  as  the  circumstances  will  permit  to  one  factor 
that  any  definite  conclusions  can  be  reached. 

A  factor  in  the  manufacture  of  butter,  the  variations  of  which  can 
be  controlled,  is  the  acidity  developed  in  the  cream.  This  factor  has 
long  been  recognized  as  important  in  determining  the  flavor  of  butter 
and  as  having  a  decided  influence  on  the  constancy  with  which 
butter  retains  its  desirable  flavors  in  storage. 

It  is  generally  taught  by  instructors  and  writers  on  dairy  subjects 
that  to  produce  good  butter  it  is  necessary  to  develop  a  certain  amount 
of  acid  in  the  cream.  The  reason  for  this  is  twofold — first,  to  develop 
a  desirable  flavor,  and,  second,  to  improve  the  keeping  quality  by 
suppressing  the  undesirable  bacteria.  McKay  and  Larsen"  state 
that  in  the  ripening  of  cream  the  lactic-acid  bacteria  suppress  other 
bacteria  which,  if  carried  into  the  butter,  would  produce  undesirable, 
changes.  It  is  recognized,  however,  that  if  the  fermentation  is  carried 
too  far  the  keeping  quality  of  the  butter  is  injured.  McKay  and 
Larsen  also  state  that  in  overripened  cream  undesirable  bacteria  may 
gain  the  ascendency  and  cause  deterioration  of  the  butter. 

Michels  6  states: 

It  has  been  found  that  butter  with  the  best  keeping  quality  is  obtained  from  well- 
ripened  cream.  It  is  true,  however,  that  butter  made  from  cream  that  has  been 
ripened  a  little  too  far  will  possess  very  poor  keeping  quality.  An  acidity  of  0.5 
per  cent  should  be  placed  as  the  limit  when  good  keeping  quality  is  desired. 


"George  L.  McKay  and  ('.  Larsen.     Principles  and   Practice  of  Butter-making. 
P.  194.     1906. 

b John  Michels.     Creamery  Butter  Makine.     P.  70.     J904. 


8  INFLUENCE    OF    ACIDITY    ON    FLAVOR    OF    BUTTER. 

These  statements  by  recognized  authorities  may  be  taken  as  an 
expression  of  the  opinion  of  instructors,  investigators,  and  butter- 
-makers  in  general.  This  opinion  seems  to  be  based,  not  on  the  results 
of  actual  experiment,  but  on  experience  in  buttermaking.  The  little 
experimental  evidence  available  on  this  question  is  conflicting  and 
inconclusive.  Patrick,  Leighton,  and  Bisbee,0  and  Patrick,  Leighton, 
and  Heileman6  concluded  that  butter  made  from  sweet  cream 
retained  its  flavor  better  than  butter  made  from  sour  cream.  The 
opposite  conclusion  was  reached  by  Dean.c  Unpasteurized  cream 
was  evidently  used  in  these  experiments. 

The  Dairy  Division  of  the  Bureau  of  Animal  Industry  therefore 
planned  to  include  in  a  general  investigation  of  the  changes  in  storage 
butter  a  scientific  and  carefully  controlled  study  of  the  influence  of  the 
acidity  of  the  cream  on  the  keeping  quality  of  the  butter  in  order  to 
determine,  if  possible,  the  proper  conditions  under  which  butter 
intended  for  storage  should  be  made.  Obviously,  results  obtained 
from  pasteurized  cream  could  not  properly  be  applied  to  butter  made 
from  unpasteurized  cream,  and  vice  versa.  Therefore  the  investi- 
gation was  planned  to  include  butter  made  from  both  pasteurized 
and  unpasteurized  cream  with  varying  degrees  of  acidity. 

EXPERIMENTS    WITH     BUTTER     MADE    FROM    CREAM    WITH 
VARYING   ACIDITY. 

The  first  lot  of  butter  in  this  investigation  was  made  in  the  creamery 
of  the  University  of  Wisconsin  dairy  school  at  Madison  in  the  summer 
of  1906.  Owing  to  the  fact  that  it  was  necessary  to  obtain  part  of  the 
cream  from  another  creamery  it  was  impossible  to  control  conditions 
as  exactly  as  was  desired,  since  in  some  cases  the  ripening  developed 
more  than  had  been  planned. 

The  entire  lot  of  cream  was  mixed;  one  half  the  quantity  was 
pasteurized  in  a  Farrington  pasteurizer  at  180°  F.;  the  other  half  was 
not  pasteurized.  After  the  pasteurization  of  the  first  half  the  two  lots 
of  cream  were  treated  in  the  same  way.  One-fourth  of  each  lot  was 
cooled  and  then  churned  as  soon  as  possible.  To  the  remaining 
cream  was  added  14  per  cent  of  the  starter  in  use  at  the  creamery. 
One-third  of  this  lot  was  cooled  and  churned  as  soon  as  possible. 
The  remaining  cream  was  allowed  to  ripen  to  about  0.45  per  cent,d 

aG.  E.  Patrick,  F.  A.  Leighton,  and  D.  B.  Bisbee.  Sweet  versus  Sour  Cream 
Butter.  Iowa  Agricultural  Experiment  Station,  Bulletin  18,  pp.  478-487.  1892. 

&G.  E.  Patrick,  F.  A.  Leighton,  and  W.  H.  Heileman.  Sweet  versus  Ripened 
Cream  Butter.  Iowa  Agricultural  Experiment  Station,  Bulletin  21,  pp.  788-791. 
1893. 

cH.  H.  Dean.  Experiments  in  Creaming  and  Butter  Making.  Ontario  Agricul- 
tural College  and  Experimental  Farms,  Twenty-first  Annual  Report  (for  1895),  pp. 
60-66.  Toronto,  1896. 

d  In  this  paper  acidity  is  expressed  as  per  cent  of  lactic  acid. 


BUTTER    MADE    FROM    CREAM    WITH    VARYING    ACIDITY.  9 

when  it  was  divided,  one  half  cooled  ami  churned,  and  the  other  half 
allowed  to  stand  forty-eight  hours  after  separation. 

The  mode  of  procedure  may  be  illustrated  by  the  following  diagram : 

Mixed  cream. 


Unpaste;irized.  Pasteurized. 


I  I                     I                      I  I                      I 

Xostirter,  Starter,  Starter.  Starter,  No  starter,  Starter,          starter.  Starter, 

not  not  ripened            over-                not  not              ripened                 over- 
ripened,  ripened.  normally.  ripened.  ripened.  ripened.  normally.  ripened. 

The  acidity  of  the  overripened  cream  developed  very  little  above 
that  of  the  normally  ripened  cream.  The  acidity  of  the  overripened 
pasteurized  cream  at  time  of  churning  was  0.52  per  cent.  The  acidity 
of  the  corresponding  unpasteurized  cream  was  0.47  per  cent.  The 
salt  and  moisture  contents  were  controlled  as  closely  as  possible  and 
showed  no  variations  which  could  be  expected  to  influence  the  results, 
except  in  the  case  of  the  unpasteurized  cream  churned  without  starter. 
In  this  case  the  salt  was  1.81  per  cent.  The  butter,  which  will  be 
designated  as  Lot  I,  was  packed  in  20-pound  tubs  and  held  seven  days 
in  the  creamery  refrigerator,  when  it  was  scored  by  Mr.  J.  G.  Moore 
and  then  shipped  by  refrigerator  freight  to  the  cold-storage  rooms  in 
Chicago.  Two  tubs  of  each  lot  were  stored  at  temperatures  of  32  °, 
10°,  and  —10°  F.  The  storage  rooms  were  held  at  these  tempera- 
tures with  very  little  variation. 

In  the  following  summer  a  quantity  of  butter  (Lot  II)  was  made 
at  Albert  Lea,  Minn.,  by  the  same  method.  This  butter  was  made 
from  milk  received  in  the  creamery  in  one  day.  Half  of  this  cream 
was  pasteurized  in  a  regenerative  Jensen  pasteurizer  at  1 70  °  F.  The 
various  lots  were  churned  at  the  following  acidities: 

Vnpastexirized:  1'ereent. 

No  starter 0.  13 

Starter  added 37 

Ripened 51 

Overripened 86 

Pasteurized: 

No  starter 13 

Starter  added 16 

Normally  ripened 51 

Overripened .  6S 

The  starter  used  in  this  cream  was  not  very  active  and  the  acidity 
developed  slowly  in  the  pasteurized  cream:  otherwise  this  butter 
could  be  taken  as  representative  of  butter  made  under  normal  com- 
mercial conditions.  The  butter  was  packed  in  sealed  10-pound  tin 
cans  and  stored,  as  was  the  Madison  butter,  at  32°,  10°,  and  —  10°  F. 

The  butter  of  Lot  I  was  scored  after  six  months  in  storage  by  Messrs. 
Credicott,  Smarzo,  KiefFer,  and  White,  and  after  nine  months  by  the 
80396— Bui.  114—09 2 


10 


INFLUENCE    OF   ACIDITY   ON   FLAVOR   OF   BUTTEE. 


three  first  named.  Each  man  scored  independently  and  without 
knowledge  of  the  history  of  the  butter.  The  average  scores  of  the 
Madison  butter  were  as  follows : 

TABLE  1. — Average  scores  of  butter  of  Lot  I. 


Storage 
Method.                                                temper- 
ature. 

Score 
when 
fresh. 

Score 
aftersix 
months' 
storage. 

Score 
after  nine 
months' 
storage. 

Unpasteurized:                                                                                          "  F. 
[        -10 
No  starter,  no  ripening                                                                {           10 

>        92 

f      90.6 
\      91 

91.3 
91.6 

32 
-10 
Starter,  no  ripening                 .  .          <           10 

1 

I        93.5 

1      87 
f      89.  5 
<       90 

86.6 
90 
92 

II            32 
[        -10 
Starter  normal  ripening                                                              <            10 

1 

I        96 

1      86.5 
f      91 
<      90 

86 
91.3 
91 

32 
-10 
Starter,  overripening.            <           10 

1        92 

[      86.5 
[      90.  05 
<      90.2 

85.3 
92.6 
No  tub. 

I           32 
Pasteurized: 
f        -10 
No  starter,  no  ripening                           <            10 

1 

1       97 

I      87.2 

(      91.3 
<      91.3 

87.5 

92.3 

92 

32 
f        -10 
Starter,  no  ripening  .  <           10 

96.5 

I      90.6 
(      91.  18 
i      91.37 

89.3 
92 
92 

32 
-10 
Starter,  normal  ripening                                                              <           10 

95 

I     "88.3 
89 
I      87.5 

89 
91.8 
90.3 

32 
f        -10 
Starter,  overripening  <            10 

92.5 

[      85.6 
85.5 
<      85.1 

84 
90.3 
84.3 

'    I            32 

I      .81.  75 

82 

The  butter  of  Lot  II  stored  at  10°  F.  was  scored  after  four  months 
by  Mr.  Credicott,  and  all  the  butter  was  scored  after  eight  months  by 
Messrs.  Kieffer  and  Smarzo.  In  the  latter  scoring  a  number  of  grades 
with  a  definite  score  were  arranged  and  the  packages  grouped  accord- 
ingly. In  all  cases  a  separate  package  was  used  for  each  scoring. 

TABLE  2. — Average  scores  of  butter  of  Lot  II. 


Method. 

Storage 
temper-  :  Score  after 
ature. 

four  months.  Score  after  six  months. 

Unpasteurized: 
No  starter  churned  sweet 

0  F. 
1        -10    

90. 

Cheesy. 

Fishy. 
Fishy. 
Curdy,  cheesy. 
Curdy,  very  poor. 
Curdy,  very  poor. 

Curdy,  cheesy. 
Curdy,  very  poor. 
Curdv.  verv  poor. 

10  i  90.    Ranc 
32    

id                      90. 

Starter  not  ripened              .            

.     .                    87. 

r        -10 

90. 

10     90.    Kane 
I           32 

id                       90. 

Starter      

90. 

—  10 

90. 

10     90.    Cold  storage  82. 
32               .     .                          82. 

Starter  overripened  .    . 

-10    

84. 

10     89.    Bad 

82. 

Pasteurized: 
No  starter  churned  sweet 

82. 

f        -10    . 

..    92. 

1            10     92.5 

90. 

Starter,  not  ripened  

32    

91. 

—10 

91. 

10     92  

'  91. 

Starter,  normal  ripening 

32 

91. 

-10    

91. 

10     91.    Cold 
32    

storage  91. 
90. 

Starter,  overripentd     

-10 

8-1. 

10     88.    Bad. 

..    82. 

32  L 

..    82. 

DISCUSSION   OF   RESULTS.  11 

A  third  lot  of  butter  (Lot  III)  was  made,  as  before,  from  one  lot  of 
cream,  one-half  of  which  was  pasteurized  at  180°  F.  After  taking 
out  one-fourth  of  each  half  to  be  churned  sweet,  15  per  cent  of  starter 
was  added.  The  different  portions  of  this  lot  of  cream  were  churned 
at  the  following  acidities: 

Unpasteurized  cream:  INT  cent. 

No  starter 0.  18 

Starter  added 32 

Ripened 54 

Overripened (it 

Pasteurized  cream: 

No  starter JG 

Starter  added 32 

Ripened 59 

Overripened 70 

This  butter  was  packed  in  sealed  tin  cans.  One  can  from  each  lot 
was  sent  to  New  York,  where  it  was  scored  when  twenty  days  old  by 
Mr.  Kieffer.  The  remainder  was  stored  at  10°  F.  and  was  again  scored 
by  Mr.  Kieffer  at  the  end  of  five  months.  The  scores  are  shown  in 
the  following  table: 

TABLE  3. — Scores  of  h utter  in  Lot  III. 


Method. 


Twenty  days  old. 


After  five  months' 
storage  at  10°  F. 


Unpasteurizcd: 

No  starter 

Starter  added '90. 

Ripened 88.     Oily i  so.     Very  fishy. 

Overripened 85 88. 

Pasteurized: 

No  starter !  915 91. 

Starter  added 9f> (to. 

Ripened :  90.    Slight  metallic....    87. 

Overripened 87.    Metallic 87. 


DISCUSSION    OF    RESULTS. 

The  score  of  the  fresh  butter  of  Lot  I  immediately  before  it  went 
into  storage  indicates  that  while  there  were  some  differences  all  of  the 
butter  was  at  least  fairly  good,  while  the  average  of  the  scores  made 
after  the  butter  had  been  in  storage  shows  marked  differences  in  a 
few  cases.  The  comments  of  the  scorers  show  that  the  butter  made 
from  unripened  unpasteurized  cream  always  developed  a  cheesy  or 
rancid  flavor.  The  butter  made  from  ripened  cream,  both  pasteurized 
and  unpasteurized,  developed  cold-storage,  fishy,  and  other  flavors 
typical  of  storage  butter.  In  all  cases  the  overripe  butter  showed 
marked  deterioration.  The  butter  made  from  pasteurized  cream 
without  starter  usually  retained  its  flavor  with  little  or  no  change. 
Even  at  32°  F.,  where  all  the  ripened  butter  showed  decided  changes, 
the  sweet -cream  butter  deteriorated  very  little.  The  score  of  the 
sweet-cream  butter  in  the  Madison  lot  was  decreased  bv  a  "woodv" 


12  INFLUENCE    OF   ACIDITY   ON   FLAVOE   OF   BUTTER. 

or  "fruity"  flavor  which  was  noticeable  at  the  top  and  sides  of  the 
package.  In  the  opinion  of  the  judges,  this  flavor  was  due  to  some 
extraneous  cause. 

The  difference  between  butter  made  from  pasteurized  sweet  cream 
and  that  from  ripened  cream,  both  pasteurized  and  unpasteurized, 
became  very  marked  after  holding  in  a  warm  room  for  a  short  time. 
Butter  made  from  pasteurized  cream  with  starter  added,  after  the 
so-called  Le  Clair  or  Credicott  method,  retained  its  fresh  flavor  better 
than  the  ripened-cream  butter,  but  was  not  quite  equal  in  keeping 
quality  to  that  made  from  sweet  pasteurized  cream. 

In  making  deductions  from  results  obtained  by  the  usual  method  of 
scoring  butter,  allowance  must  be  made  for  certain  variations  due  to  the 
sense  of  taste,  which  is  not  adapted  to  expression  in  mathematical 
terms.  However,  after  making  allowance  for  the  personal  tastes  and 
variations  that  can  not  be  avoided  in  butter  scoring,  it  is  evident  from 
the  results  shown  in  the  tables  that  some  factor  having  a  deleterious 
influence  on  the  butter  was  developed  with  the  ripening  of  the  cream. 
The  action  of  this  factor  is  especially  evident  in  the  cream  allowed  to 
stand  beyond  the  usual  ripening  period,  although  it  is  not  necessarily 
accompanied  by  a  marked  increase  in  acidity,  as  is  shown  by  the 
overripened  butter  of  Lot  I.  In  determining  what  this  deleterious 
factor  is,  it  should  be  remembered  that  these  changes  took  place  at 
temperatures  of  20  and  even  40  degrees  below  the  freezing  point. 
We  know  that  a  comparatively  high  acidity  was  developed  in  the 
cream  from  which  this  butter  was  made,  but  there  is  also  the  possi- 
bility that  other  influences  having  little  connection  with  the  acid  may 
have  developed  to  affect  the  flavor  of  the  butter. 

The  direct  action  of  bacteria  in  causing  changes  at  these  temper- 
atures is  obviously  excluded,  but  an  indirect  action  may  be  found  in 
the  possibility  that  enzymes  are  secreted  in  the  cream  by  bacteria  and 
that  these  enzymes  are  able  to  act  even  at  the  low  temperatures  at 
which  this  butter  was  stored. 

DETERMINATIONS    OF    BACTERIA    IN    THE    BUTTER. 

Qualitative  and  quantitative  determinations  of  the  bacteria  in  the 
cream  and  butter  were  made  according  to  the  following  methods: 
Gelatin,  and  in  some  cases  both  gelatin  and  agar,  plates  were  made  of 
the  cream  at  the  various  stages  of  the  ripening.  All  media  used  con- 
tained 2  per  cent  lactose  and  were  corrected  to  a  reaction  of  +0.2 
Fuller's  scale,  with  the  exception  of  plates  made  from  Lot  III,  in 
which  the  reaction  was  +1.0.  Anaerobic  plates  showed  no  bacteria 
not  present  on  the  ordinary  aerobic  plates.  In  making  plates  from  the 
butter,  samples  of  5  to  10  grams  each  were  taken,  with  proper  precau- 
tions to  prevent  contamination,  from  five  or  six  different  places  in 
each  tub.  The  samples  were  melted  at  40°  C.,  and  after  thorough 


DETERMINATIONS  OF  BACTERIA   IN    THE   BUTTER. 


13 


mixing,  5  grams  of  each  were  weighed  into  flasks  containing  500  c.  c.  of 
sterile  water.  These  flasks  were  held  in  a  water  bath  until  the  tem- 
perature reached  40°  C.  anil  were  shaken  vigorously  to  insure  a  thor- 
ough distribution  of  the  bacteria.  Plates  with  varying  dilutions  were 
made  in  the  usual  way. 

The  results  of  the  bacterial  determinations  are  given  in  Table  4  for 
the  Lot  I  butter,  in  Table  5  for  the  Lot  II  butter,  and  in  Table  6  for  the 
Lot  III  butter. 

TABLE  4. — Bacteria  in  butter  of  Lot  I. 


Method. 

Initial        temped' 
number.     *™t*™'\ 

After  six 
months' 
storage. 

After  nine 
months' 
storage. 

Unpasteurized  cream: 

°  F. 
(        -10 
8,983,000   \            10 

2.300,000 
2,360.  000 

3,090.000 

|            32 
-10 
2.893,000   {            10 

1,195.000 

872.  500 
730  000 

816.000 
906.  1X10 
351,000 

1            32 
-10 
3.924,000   *            10 

531,000 
1,257,7.50 
1  107  500 

:  02,  ooo 

949,000 
1  O'lii  000 

Overripened  

32 
-10 
9,825,000    I             10 

349.825 
24,  727,.  500 
1,470,  166 

2I1.000 
1,187,00(3 
No  butter. 

Pasteurized  cream: 
Churned  sweet  .  .                  

1            32 

!|      -10 

386,166   \            10 

554,000 

146,625 
134,166 

124,000 

49,000 
106.214 

Starter  added 

32 
|         -10 
2,800,000   <            10 

6,  870,  000 
855.  7.50 
245,2.50  . 

174.000 

;  20,  ooo 

102.000 

Normal  ripening  

32 
(         -10 
945,000   <            10 

305,000 
110,000 
275.000 

253.000 
10,.  500 
6,600 

Overripened 

32 

-10 
1,956,000   i            10 

265.000 
67,.  500 
300,  166 

32,876 

11,800 
16,  100 

1            32 

24,500 

8,100 

TABI.K  5. — Bacteria  in  cream  and  but'rr  of  Lot  II. 


Method. 


burning.       ««»*>• 


IT  storage. 


Not  pasteurized: 
No  starter  66,  100,  000 

11,900,000   ] 

-10 
10 

490,000 
365,  000 

Starter  added  <    553,.  500,  (KX) 

12,800  000   | 

32 
-10 
10 

i  53,  000 
726,000 
133,  (XXI 

Normal  ripening  779,000,000 

4,260,000    ] 

32 
-10 
10 

64,000 
376,  (XX) 
297,  (XX) 

32 

10 

106,000 

Overripened  620,000,000 

10 

13,  (XX) 

Pasteurized: 
No  starter  27000 

491  500   < 

32 

-10 
10 

5,000 
28,  (XX) 

32 

Starter  added  .                                                               85  7.50  000 

8°6  000   < 

-10 
10 

90,000 

Normal  ripening  7ft  1,000,  000 

13,650,000   < 

32 

-10 
10 

241,  (XX) 
38!  .IXX) 
4.50,  (XX) 

Overripened  .                                                          880  000  000 

38  400  000   | 

32 
-10 
10 

35.600 
172.000 
1   KX)  000 

32 

23,000 

14  INFLUENCE    OF    ACIDITY    ON    FLAVOE    OF   BUTTER. 

TABLE  6. — Bacteria  in  cream  and  butter  of  Lot  III. 


Method. 

Bacteria  per  cubic  centi- 
meter in  cream  at  time 
of  churning. 

Bacteria  per  grain  in 
fresh  butter. 

Bacteria  per  gram  in 
butter  after  stor- 
age at  10°  F. 

Total. 

Liqueflers. 

Total. 

Lique- 
fiers. 

Total. 

Lique- 
flers. 

Unpasteurized: 
No  starter.  . 

43,800,000 
226,000,000 
258,500,000 
362,  500,  000 

195,  500 
162,500,000 
1,000,000,000 
526,000,000 

1,750,000 
540,  000 
75,000 
40,000 

13,300 
None. 
None. 
None. 

3,755,000 
7,233,000 
12,766,000 
3,136,000 

88,500 
10,300,000 
11,520,000 
24,666,000 

161,000 
94,000 
None. 
None. 

20,000 
3,000 
None. 
None. 

610,000 
563,000 
469,500 
87,000 

a  1,344,  000 
2,275,000 
278,500 
420,000 

85,000 
1,000 
None. 
2,000 

56,000 
1,500 
400 
None. 

Starter  added     

Ripened 

Overripened             

Pasteurized: 
No  starter 

Starter  added  

Ripened 

Overripened  .              

a  Development  of  O'idium  lactis  and  Bacterium  lactis  aerogenes. 

There  is,  of  course,  always  the  possibility  that  bacteriological  meth- 
ods do  not  show  true  bacteriological  conditions.  Assuming  that  the 
gelatin  plates  gave  a  correct  indication  of  the  nature  and  number  of 
the  bacteria  present,  there  is  little  in  the  results  in  the  Lot  I  butter 
to  connect  the  bacteria  in  any  direct  way  with  the  changes  in  the 
butter.  The  unpasteurized  cream  contained  a  total  of  9,000,000  bac- 
teria per  cubic  centimeter,  of  which  300,000  were  of  the  liquefying 
type.  There  was  an  increase  for  a  short  time  of  the  liquefying  bac- 
teria, but  these  were  soon  suppressed  by  the  lactic-acid  bacteria. 
When  the  maximum  development  was  reached  the  lactic  bacteria 
decreased  slowly.  There  was,  however,  no  apparent  growth  of  any 
other  kind  of  bacteria.  The  freshly  pasteurized  cream  contained 
1,192  bacteria.  There  was  a  small  increase  of  nonlactic  bacteria,  but 
this  was  soon  checked  by  the  lactic  bacteria,  and  the  subsequent 
development  agreed  with  that  observed  in  the  unpasteurized  cream. 

The  cream  from  which  Lot  II  was  made  contained  66,100,000  bac- 
teria per  cubic  centimeter,  which  were  reduced  by  pasteurization  to 
27,000.  In  the  unpasteurized  cream  the  lactic-acid  bacteria  soon 
gained  the  ascendency  and  suppressed  all  other  kinds.  There  was  a 
considerable  development  of  bacteria  of  the  aerogenes  type  in  the 
normally  ripened  pasteurized  cream,  but  these  were  suppressed  in  the 
overripe  cream  by  the  lactic-acid  bacteria.  Otherwise  the  plates 
showed  no  bacteria  which  could  be  expected  to  influence  the  flavor. 

The  bacteria  in  the  cream  of  Lot  III  followed  the  same  general 
course.  There  was  no  appreciable  growth  of  gas-forming  bacteria  in 
this  cream,  but  in  the  overripened  unpasteurized  cream  there  was  a 
small  development  of  O'idium  lactis.  Ten  days  elapsed  after  this  but- 
ter was  taken  from  storage  before  it  was  received  at  the  laboratory. 
During  this  time  it  was  doubtless  held  at  temperatures  within  the 
thermal  growth  limits  of  ordinary  bacteria.  There  wTas  a  distinct 
increase  of  bacteria  in  the  pasteurized  sweet-cream  butter  in  which 


DETERIORATION    POSSIBLY   DUE    TO    ENZYMES.  15 

the  two  inhibiting  factors,  acid  and  salt,  were  low.  This  bacterial 
growth  may  have  been  responsible  for  the  deterioration  of  this  butter. 

In  all  the  butter  stored  at  10°  and  —10°  F.  there  was  a  gradual 
decrease  in  the  total  bacteria.  This  was  usually  slightly  more  rapid 
at  the  higher  temperature,  but  this  difference  in  the  rate  of  decrease 
was  sometimes  obscured  by  errors,  due  largely  to  the  diiliculty  of 
securing  a  representative  sample.  At  32°  F.  this  decrease  was  usu- 
ally much  more  pronounced  than  at  the  lower  temperatures.  In 
several  cases,  however,  there  was  an  actual  increase  confined  chiefly. 
if  not  entirely,  to  the  torula  group  of  yeasts.  In  one  package  the 
development  was  sufficient  to  make  an  actual  increase  in  the  total 
number  of  bacteria,  which  in  the  ordinary  technique  includes  yeasts 
as  well  as  bacteria.  Usually  the  growth  of  yeasts  was  so  much  less 
than  the  decrease  in  bacteria  that  the  total  number  showed  a  decrease. 
It  has  been  demonstrated  that  some  members  of  this  group  of  yeasts 
may  cause  a  decomposition  of  butterfat.a 

In  some  cases  the  change  in  the  flavor  of  the  butter  stored  at  32°  F. 
might  be  accounted  for  by  this  development  of  yeasts,  but  in  others 
in  which  there  was  an  equal  deterioration  there  was  no  appreciable 
increase  of  yeasts  or  bacteria. 

The  inference  should  not  be  drawn  that  the  writers  exclude  the 
action  of  bacteria  as  a  factor  in  causing  changes  taking  place  in 
butter.  It  is  undoubtedly  true  that  not  only  the  flavor  of  the  fresh 
butter  but  the  change  in  flavor  after  the  butter  is  made  may  be 
influenced  by  the  bacterial  growth  in  the  cream,  and  under  certain 
conditions  bacteria  and  yeasts  may  grow  in  the  butter  itself.  The 
uniform  deterioration  of  the  high-acid  butter  at  the  lower  tempera- 
tures, however,  could  not  be  accounted  for  in  this  way. 

POSSIBLE  ACTION  OF  ENZYMES  IN  DETERIORATING    HIGH-ACID  BTTTER. 

A  plausible  explanation  of  the  changes  may  be  found  in  the  possible 
production  of  enzymes  by  the  lactic-acid  bacteria,  which  if  carried 
into  the  butter  would  continue  to  act,  as  has  been  previously  sug- 
gested, even  at  the  lower  temperatures  at  which  it  was  stored.  It  is 
doubtful  if  enzymes  are  excreted  by  the  lactic-acid  bacteria,  but  it  is 
well  established  that  all  cells  contain  enzymes  which  rapidl\T  bring 
about  the  destruction  of  the  cell  after  its  death.  Even  the  minute 
amounts  of  the  decomposition  products  of  the  bacterial  cells  might 
affect  the  flavor  of  butter.  Moreover,  it  is  possible  that  enzymes 
not  normally  excreted  are  liberated  by  the  natural  death  and  dis- 
integration of  the  cell.  This  is  at  least  a  possibility  that  can  not  be 
disregarded. 


n  L.  A.  Rogers.     Studies  upon  the  Keeping  Qualities  of  Butter. — I.  Canned  Butter. 
United  States  Department  of  Agriculture,  Bureau  of  Animal  Industry,  Bulletin  57. 


16 


INFLUENCE    OF   ACIDITY    ON    FLAVOR    OF    BUTTER. 


The  situation  in  the  unpasteurized  cream  is  complicated  by  the 
possible  action  of  the  enzymes  of  the  milk,  which  include  proteolytic, 
lipolytic,  and  oxidizing  enzymes,  but  these  enzymes  would  be 
destroyed  by  the  pasteurization  of  the  cream,  which,  as  we  have 
seen,  did  not  prevent  the  deterioration. 

If,  as  suggested,  enzymes  are  liberated  in  any  way  by  the  lactic-acid 
bacteria,  butter  made  from  cream  heated  sufficiently  after  ripening 
to  destroy  the  enzymes  should  not  change  at  temperatures  low  enough 
to  prevent  the  growth  of  bacteria  and  other  organisms.  In  Table  7 
are  given  the  results  of  an  experiment  in  which  10  per  cent  of  starter 
was  added  to  sour  hand-separated  cream,  the  mixture  pasteurized 
at  once  at  180°  F.,  cooled  properly,  and  churned.  One-half  of  this 
cream  was  pasteurized,  starter  added,  and  allowed  to  ripen  over 
night. 

TABLE  7. — Showing  changes  in  butter  made  from  cream  pasteurized  after  ripening. 


Score 

after  one 

Storage 

Score 

Score 

Method. 

week 

tempera- 

after two 

after  five 

(before 

ture. 

months. 

months. 

storage). 

a.  Sour  hand-separator  cream,  10  per  cent  starter  added,  pas- 
teurized at  180°  F.,  cooled,  and  churned. 

1           93 

|        -10 
10 
32 

83.7 
84.7 

82.7 

84.2 
84.0 
85.0 

6.  Half  of  a.  Pasteurized  at  180°  F.,  10  per  cent  starter  added, 
ripened  over  night,  cooled,  and  churned. 

|           92 

-10 
10 
1           32 

83.2 

83.7 
S3.  7 

83.5 
83.5 

84.0 

When  these  lots  of  butter  went  into  storage  one  week  after  making, 
they  scored  93  and  92,  respectively.  In  two  months  both  lots  had 
developed,  regardless  of  storage  temperature,  a  rank,  fishy  flavor. 
All 'enzymes  would  be  nearly  if  not  quite  destroyed  by  the  tempera- 
ture to  which  this  cream  was  exposed.  To  assume  that  this  marked 
change  in  flavor  was  caused  by  the  development  of  bacteria  would  be 
contrary  to  our  experience  with  other  butter.  These  results  have 
been  duplicated  many  times  in  the  course  of  other  investigations. 

One  lot  of  butter  was  made  in  our  experimental  creamery  in  Albert 
Lea  in  the  following  way:  The  fresh  cream  was  pasteurized  at  170° 
F.  To  this  was  added  20  per  cent  of  starter,  and  one-fourth  was 
cooled  and  churned  at  once  (designated  as  a).  Another  fourth  wras 
ripened  overnight  to  an  acidity  of  0.41  per  cent  (6).  The  remainder 
was  allowed  to  stand  forty-eight  hours.  At  this  time  the  acidity  was 
0.59  per  cent.  Half  of  this  remainder  was  properly  cooled  and 
churned  (c),  and  the  remaining  fourth  heated  in  a  vat  at  158°  F.  for 
ten  minutes,  after  which  it  was  cooled  and  churned  (d).  These 
butters  were  examined  by  numbers  only  when  they  went  into  storage 
one  week  after  making,  and  again  after  four  and  one-half  months  of 


INFLUENCE   OF   LACTIC    ACID. 


17 


storage  at  a  temperature  of  10°  F.     The  results  of  the  examination 
are  given  below: 

TABLE  8. — Changes  in  butter  made  from  cream  pasteurized  ufier  ripening. 


Portion  and 
method. 


o.  Starter  added  — 
6.  Ripened 

c.  Overripened 

d.  Overripened  and 

heated. 


Acidity. 


Result  afier  one  week. 


Per  cent. 


Perfectly  good. 


0.  41     Very  nice  butter;  good  aroma 

.  59     Unclean 

.  59     Extremely  unclean 


Score  after  four  and  one-half  months 
storage  at  10°  F. 


92.  Tallowy. 

92.  Tallowy.   Slight  storage. 

91.  Stale-water  flavor. 

87.  Old,  tallow,  rancid,  grease. 


It  is  apparent  that  the  deleterious  effect  of  high  acidity  was  not  duo 
to  any  organism,  enzyme,  or  other  substance  which  can  be  destroyed 
by  heat.  It  is  evident,  then,  that  some  by-product  of  bacterial 
growth,  unaffected  by  heat,  had  a  marked  influence  on  the  flavor 
of  the  butter.  It  is  probable  that  this  was  a  by-product  of  the  lactic- 
acid  bacteria  and  that  the  by-product  was  lactic  acid  itself. 

INFLUENCE    OF   LACTIC    ACID    ON    FLAVOR    OF    BUTTER. 

A  number  of  experiments  have  been  made  to  determine  the  influ- 
ence of  acidity  developed  in  the  cream  by  the  addition  of  lactic  acid. 
These  have  invariably  given  results  similar  to  those  shown  in  Table 
9.  In  securing  the  results  shown  in  this  table  one-third  of  a  lot  of 
pasteurized  cream  was  cooled  and  churned  at  once  («).  To  the  re- 
mainder were  added  small  portions  of  chemically  pure  lactic  acid 
until  it  showed  an  acidity  of  0.36  per  cent.  Half  of  this  was  cooled 
and  churned  on  the  following  morning  (&).  The  acidity  of  the 
remaining  .third  was  increased  to  0.41  per  cent,  cooled,  held  over- 
night, and  churned  the  next  day  (c).  The  butter  remained  in 
the  creamery  refrigerator  two  weeks,  when  it  was  examined  by  num- 
bers only,  and  snipped  to  storage  at  10°  F.  It  was  examined  again 
after  three  and  a  half  months  in  storage  with  the  following  results: 

TABLE  9. — Influence  of  lactic  acid  on  the  flavor  of  butter. 


Portion  and  method. 

Acidity. 

Condition  after  two  weeks. 

Score  after  three  and 
one-half  months  in 
storage  at  10°  F. 

Per  cent. 
0  099 

Good 

9H  5.  Sweet. 

6.  Lactic  acid  added  
c.   Lactic  acid  added... 

.  300 
.444 

Oily,  unclean  
oilv,  decomposed  fat... 

89.  Sweet,  fruity. 
87.  Sweet,  oilv. 

RESULT  OF  PRODUCING  ACIDITY  WITH  OTHER   ACIDS  THAN   LACTIC  ACID. 

Similar  results  have  been  obtained  with  butter  made  from  cream 
acidified  with  acid  other  than  lactic  acid.  These  butters  wen1  made 
in  the  following  manner:  Sweet  cream  sufficient  to  make  three1  churn- 


18 


INFLUENCE    OF    ACIDITY    ON    FLAVOR    OF    BUTTER. 


ings  was  pasteurized  in  a  continuous  pasteurizer  at  170°  F.  One- 
third  was  cooled  and  churned  at  once  (a).  To  the  remaining  two- 
thirds  acid  was  added  slowly  until  the  acidity  expressed  as  lactic 
acid  equaled  about  0.22  per  cent.  This  portion  was  divided  and 
one-half  cooled  (b).  The  remaining  portion  was  acidified  to  about 
0.4  per  cent  and  cooled  (c).  Portions  Z>  and  c  were  churned  on  the 
following  day.  Lot  1  was  acidified  with  lactic  acid,  lot  2  with  acetic 
acid,  and  lot  3  with  hydrochloric  acid. 

There  was  a  slight  development  of  bacteria  in  these  creams,  which 
was  evidently  checked  by  the  higher  acidity.  The  greater  part  of 
the  bacteria  present  were  of  the  lactic-acid  type,  or  had  no  appre- 
ciable effect  on  milk.  This  butter  was  packed  in  sealed  cans  and  a 
few  days  after  making  was  shipped  to  storage  and  was  examined  by 
Mr.  Credicott  when  about  15  days  old.  The  results  are  given  in 
Table  10. 

TABLE  10. — Showing  the  influence  of  different  acids  on  the  flavor  of  butter. 


Lot. 

Acid  added. 

Acidity 
of  cream. 

Score  after  fifteen  days. 

1  0  

None... 

Per  cent. 
0.144 

88 

Trifle  unclean  and  very  greasy. 

1  b  

Lactic  

.216 

88 

Do. 

1  c. 

do.... 

.432 

8fi 

Fishy  and  greasy. 

2a  
26  

None  
Acetic... 

.126 
.216 

90. 

87 

Trifle  oily,  body  weak  and  greasy. 
Very  greasy,  and  rancid  on  fishy  order. 

2c  

do  

.350 

S-l 

Very  flshv  and  greasy. 

3o  
36  

None  
Hydrochloric  . 

.126 
.225 

90. 
90 

Clean  but  greasy. 
Trifle  unclean  and  oily. 

3c  

do  

.450 

84 

Very  fishy,  greasy. 

This  table  shows  that  this  action  is  not  peculiar  to  lactic  acid  or 
even  to  organic  acids. 

It  would  appear,  therefore,  that  the  acidity  of  the  cream  has  a 
direct  influence  on  the  changes  in  the  butter.  This  is,  of  course, 
usually  complicated  by  the  influence  of  other  factors,  many  of  which 
are  still  undetermined.  Just  what  action  the  acid  has  and  what  parts 
of  the  butter  are  changed  to  bring  about  the  undesired  flavors  we 
are  not  prepared  to  say  at  this  time,  but  investigations  are  in  progress 
which  it  is  hoped  will  throw  some  light  on  the  complex  chemical 
changes  controlling  the  flavor  of  butter. 

THE    MANUFACTURE    OF    COMMERCIAL.    BUTTER    FROM     SWEET 

CREAM. 

To  the  person  interested  in  the  application  of  these  results  to 
practice  it  is  obvious  that  butter  which  market  conditions  require  to 
be  held  for  any  length  of  time  should  be  made  with  as  little  acid  as 
possible.  This  is  especially  true  of  butter  held  for  several  months 
in  cold  storage  and  butter  canned  for  use  on  shipboard  or  for  export 
to  tropical  countries.  While  the  object  of  this  investigation  was  to 
determine  the  causes  of  change  in  butter,  the  results  allow  some  com- 


COMMERCIAL   BUTTER   FROM   SWEET   CREAM. 


19 


parisons  to  be  made  of  the  commercial  value  of  the  different  methods 
of  butter  making.  The  deterioration  in  storage  of  butter  made  from 
overripened  cream  is  well  known,  and  this  investigation  has  shown 
clearly  that  butter  made  from  cream  ripened  according  to  the  usual 
creamery  practice  changes  much  more  than  butter  made  with  a  low 
acidity.  A  number  of  trials  were  made  to  determine  if  adding 
sufficient  starter  to  cream  to  improve  the  flavor  of  the  butter  would 
seriously  impair  the  keeping  quality. 

The  keeping  quality  of  butter  made  from  sweet  pasteurized  cream 
is  compared  in  the  next  table  with  that  of  butter  made  with  starter. 
The  scores  given  in  this  table  are  the  average  scores  of  six  lots  of 
butter  made  in  the  creamery  at  Bloomer,  Wis.  The  cream  from 
which  this  butter  was  made  was  pasteurized  in  a  Farrington  pasteur- 
izer at  temperatures  varying  from  155°  to  175°  F.  The  lot  was 
divided,  a  large  starter  added  to  one-half,  and  each  portion  cooled 
and  churned  at  once.  In  a  few  cases  one-half  was  ripened,  but  this 
butter  was  so  much  poorer  than  the  sweet-cream  butter  that  it  was 
not  stored.  The  scorers  were  Messrs.  Kieffer,  Smarzo,  Credicott, 
and  White : 


TABLE  11. — Showing  relative  keeping  quality  of  butter  made  from  pasteurized  sweet 
sweet  cream  with  starter  added,  and  normally  ripened  cream. 


cream, 


Average     Average 


O  WJI  U^t 

Lot  an<l  method.                                                     temper- 
ature. 

score           score 
after  four  aftereight 
months,     months. 

1        ~1( 

92.  6              93.  0 

la. 

Sweet  cream  U 

91.3              93.  1 

32 

89.3              91.0 

91.0              92.5 

I  '.. 

Starter  added  —                                                                                                  10 

91.3              92.3 

1           32 

89.  3              89.  0 

-10 

90.  3              92.  6 

2  a. 

Sweet  cream  10 

90.  8              92.  6 

1            32 

90.  6              88.  6 

-10 

92.2              94.3 

26. 

Starter  added  {            11 

92.  1  !            93.  r, 

1            32 

90.  0              92.  0 

-K 

90.  6              92.  1 

3  a. 

Sweet  cream  K 

90.6              91.8 

32 

89.  2              88.  3 

-1( 

90.  4               88.  6 

3e. 

Ripened  normally  .                 \          K) 

88.  5              88.  6 

32 

8.1.  7              83.  3 

91.8               92.7 

4  a. 

Sweet  cream  K 

91.4              92.7 

1            32 

92.  0              93.  0 

I         -10 

91.9              93.0 

46. 

Starter  added  K 

91.2              928 

1           32 

87.  3              87.  3 

1        ~  '^ 

91.1               93.0 

.".  i>. 

Sweet  cream  1  1 

91.5               93.0 

3-2 

92.2               91.5 

I         —10 

92.  1              93.  0 

56. 

Starter  added  10 

90.  9              92.  1 

1           32 

88.  0              Sli.  0 

[        -10 

91.3              93.'. 

6  a. 

Sweet  cream  10 

90.6              91.5 

1           32 

89.  6              92.  2 

-10 

91.  0              93.  0 

66. 

Starter  added  )           10 

90.  8              92.  7 

1            32 

87.  3              89.  3 

20 


INFLUENCE    OF    ACIDITY    ON    FLAVOR    OF    BUTTER. 


The  foregoing  table  is  summarized  in  Table  12,  which  gives  the 
average  of  the  scores  of  the  six  lots  of  sweet-cream  butter  and  of  the 
five  lots  of  butter  made  from  sweet  cream  with  starter: 

TABLE  12. — Showing  average  scores  of  butter  made  from  pasteurized  sweet  cream  and  sweet 

cream  with  starter  added. 


Method. 

Storage 
tempera- 
ture. 

Average 
score 
after  four 
months. 

Average 
score 
after  eight 
months. 

Sweet  cream  (six  lots) 

"F. 
\        -10 
10 

91.28 
91  03 

92.81 
92  45 

Starter  added  (five  lots)   ... 

32 
-10 
10 

90.32 
91.64 
91  26 

90.73 
93.16 
92  68 

I           32 

88.38 

88.72 

The  foregoing  table  shows  that  at  the  two  lower  temperatures 
there  was  little  or  no  advantage  in  the  sweet-cream  butter  over  that 
with  the  starter,  but  at  32°  F.  there  was  a  decided  difference  in  favor 
of  the  sweet-cream  butter.  Butter  has  been  made  under  commercial 
conditions  by  this  method  in  large  quantities,  and  when  sold  after 
several  months  in  storage  was  considered  highly  satisfactory. 

In  the  work  described  in  the  foregoing  pages  we  have  given  little 
attention  to  sweet-cream  butter  for  immediate  consumption.  We 
have,  however,  a  number  of  scores  of  fresh  butter,  most  of  which  are 
comparisons  of  butter  made  from  pasteurized  sweet  cream  with  and 
without  starter  added. 

In  three  lots  sent  to  the  New  York  market  the  butter  made  from 
cream  with  starter  added  was  scored  from  1  to  2|  points  higher  than 
the  sweet-cream  butter.  On  the  other  hand,  in  eight  lots  of  butter 
sent  to  the  Fox  River  Butter  Company  the  average -score  of  the  sweet- 
cream  butter  was  93.7,  against  93.3  for  the  butter  with  starter. 
The  difference  in  favor  of  the  sweet-cream  butter  was  greater  in  the 
butter  eight  or  ten  days  old  at  the  time  of  scoring,  while  in  the  butter 
scored  immediately  after  making  the  highest  score  was  given  to  the 
butter  with  starter.  In  four  lots  in  which  sweet-cream  butter  was 
compared  with  butter  made  from  cream  ripened  in  the  normal 
manner,  the  former  received  an  average  score  of  94  against  91.2  for 
the  ripened-cream  butter. 

The  difference  between  the  scores  given  the  butter  sent  to  New 
York  and  that  sent  to  the  Fox  River  Butter  Company  may  be 
explained  by  the  demand  of  the  market  and  the  personal  tastes  of 
the  scorers.  The  New  York  market  calls  for  a  butter  with  a  decided 
flavor,  and  the  mild  sweet-cream  butter  consequently  received  a 
low  scbre.  The  scorer  at  the  Fox  River  Butter  Company,  on  the 
other  hand,  gives  a  good  score  to  a  butter  free  from  any  objectionable 
flavors.  The  scores  of  these  lots  are  given  in  Table  13: 


CONCLUSIONS.  21 

TABLE  13. — Scores  of  fresh  butter  made  from  pasteurized  sweet  cream,  siccct  (ream  vith 
starter  added,  and  cream  ripened  normally. 


Fox 

OW  York    'V,;';;rr 

Lot  ami  method.  (Kieffen 

,  any 
scon1. 


a.  Sweet  cream in 

6.  Starter  added U4 

a.  Sweet  cream •  '.rj. .",  in 

6.  Starter  added <i;{.  .j  <rj 

o.  Sweet  cream 1*2  !M 

b.  Starteradded 94  ;rj. 

id 
I 
• 


|  c.  Ripened. 
.  ( .0.  Sweet  cream. . 
\  b.  Starter  added . 
.(  a.  Sweet  cream.. 
*l  6.  Starteradded. 
a.  Sweet  cream.. 
6.  Starter  added . 
-|  a.  Sweet  cream.. 
I  6.  Starteradded. 


fj 
°\ 


Sweet  cream. 
b.  Starteradded. 
a.  Sweet  cream.. 


"1  6.  Ripened.. 
1flf  a.  Sweet  cream. 

1U\  b.  Ripened 

..fa.  Sweet  cream. 
n\  b.  Ripened 


These  results  show  at  least  that  butter  may  be  made  from  sweet 
cream  which  will  after  long  storage  at  comparatively  high  tempera- 
tures be  classed  as  good  butter  b}*  competent  judges.  The  method 
for  making  this  butter  is  so  simple  that  a  uniform  output  with  little 
danger  from  undesirable  fermentations  can  be  insured.  The  trouble 
and  expense  of  starters  are  eliminated.  In  churning  sweet  cream  it 
is  essential  that  careful  attention  be  given  to  the  churning  tempera- 
ture and  to  the  speed  of  the  churn,  otherwise  there  is  likely  to  be  an 
unnecessary  loss  of  fat  in  the  buttermilk.  Care  should  be  taken  in 
storing  butter  made  from  sweet  cream  to  guard  against  woody  or 
other  extraneous  flavors,  which  are  likely  to  be  more  noticeable  in 
this  mild-flavored  butter  than  in  butter  with  a  high  flavor. 

The  Dairy  Division  is  not  advising  the  adoption  of  this  method  for 
general  use,  but  its  trial  for  butter  intended  for  storage  is  recommended. 

CONCLUSIONS. 

Butter  frequently  undergoes  marked  changes,  even  when  stored 
at  very  low  temperatures. 

These  changes  are  more  marked  as  the  acidity  of  the  cream  from 
which  the  butter  is  made  is  increased. 

Xo  bacteria  were  found  in  the  cream  or  the  butter  which  could 
reasonably  be  expected  to  be  the  cause  of  the  more  rapid  deteriora- 
tion of  the  high-acid  butter. 

The  changes  in  the  high-acid  butter  were  not  checked  by  heating 
the  ripened  cream,  which  shows  that  they  were  not  brought  about  by 
enzymes  secreted  with  or  in  the  cream  and  carried  into  the  butter. 


22  INFLUENCE    OF   ACIDITY    ON    FLAVOR    OF    BUTTER. 

Marked  changes  of  an  undesirable  nature  were  produced  in  butter 
by  acidifying  pasteurized  cream  with  various  acids.  These  changes 
did  not  take  place  all  at  once,  but  were  of  a  progressive  nature. 

The  results  indicate  that  the  acid  developed  normally  in  the  cream 
by  the  action  of  the  lactic-acid  bacteria,  or  added  directly  to  the  cream 
in  the  form  of  pure  acid,  brings  about  or  assists  in  bringing  about  a 
slow  decomposition  of  one  or  more  of  the  labile  compounds  of  which 
butter  is  largely  composed. 

Butter  can  be  made  commercially  from  sweet  pasteurized  cream 
without  the  addition  of  a  starter.  Fresh  butter  made  in  this  way 
has  a  flavor  too  mild  to  suit  the  average  dealer,  but  it  changes  less  in 
storage  than  butter  made  by  the  ordinary  method,  and  can  be  sold 
after  storage  as  high-grade  butter. 

O 


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A     001  087  835     3 


